I remember back in 1990 speaking to an interface expert admitting he was wrong about the then new-fangled color monitors starting to take over for green-screen monochrome monitors. I also remember my own reluctance to move to color printing. I made lots of money selling the early HP LaserJets, so why change? Books aren't in color, at least outside kids books and some garish Illustrated Guides for various computer topics. Why get all colory?
Since then, I've found three good reasons to print in color, even for standard business documents that everyone else just spits out of their laser printers. First, I want my documents to stand out. Second, to highlight important information. Finally, to more fully engage the visual learners in my audience.
When my documents (proposals) sit on a potential client's desk, I want them to stand out. One of the easiest and least expensive ways to stand out is judicious use of color. When other proposals list the client name in a bigger, bolder font, the client likes that. When I put the client's name in color, along with their color logo, clients love that.
Politicians know a red tie projects a powerful image. Splashes of color draw the eye immediately to that part of the page, away from the black and white sections. But use this sparingly. Politicians also know a red suit is far too much, a good lesson to remember when jumping into color printing.
Finally, many among us learn better from visual information than text. Highlighting sections helps these people find and absorb the key points. Diagrams or charts, which should always be in color, will impart your information better to visual learners than another paragraph of text. If you don't believe me, ask CraigsList. Those items with pictures, always in color, sell faster and for more money. Keep that in mind for your own proposals and training materials.
Don't go overboard, like those early Macintosh users who littered pages with 27 fonts just because they could. No one wants to read lavender text on a chartreuse background. But when you use a Warning heading, put that in red. When you talk about energy savings, put that headline in green. Use color to enhance your position subtly and effectively.